Study reveals impacts of past climates on biodiversity

Past climate may have a stronger impact on biodiversity than was previously thought, according to new EU-funded research published in the journal Ecography. The findings have implications for our understanding of how species are likely to react to the effects of climate change.

The question of why some regions are home to more species than others has fascinated scientists for centuries. Over the past 20 years, many studies have indicated that today’s distribution of species is determined by current patterns of energy and water. This is known as the ‘contemporary climate’ hypothesis.

However, an alternative view called the ‘historic climate’ hypothesis proposes that current species richness reflects responses to historic climate changes.

In this latest study, researchers investigated reptile and amphibian species in Europe with a view to determining the contribution of past and current climate variability to today’s distribution of these species. Their results challenge the view that contemporary climate patterns alone can explain and predict species diversity.

‘Our results are striking in that they contradict previous studies of large-scale patterns of species richness,’ commented Dr Carsten Rahbek of the University of Copenhagen. ‘They provide the first evidence, using a quantitative analytical approach, that historic climate can contribute to current patterns of richness independently of, and at least as much as, contemporary climate.’

The findings have important implications, as Dr Miguel Araújo of Spain’s National Museum of Natural Sciences, explains. ‘An understanding of the mechanisms that generate and maintain diversity provides valuable insights for predicting the impacts of contemporary climate changes on biodiversity,’ he said.

‘If contemporary climate does drive species richness, then current climate variables could be used to accurately predict the effects of climate change on biodiversity. If, as shown in our study, the mechanisms underlying contemporary patterns of species richness are in fact strongly influenced by the history of climate, then current climate predictions may be seriously misleading and alternative approaches to predict the effects of climate change on biodiversity must be developed.’

EU support for the project came from the ECOCHANGE (‘Challenges in assessing and forecasting biodiversity and ecosystem changes in Europe’) project, which is funded under the ‘Sustainable development, global change and ecosystems’ thematic area of the Sixth Framework Programme (FP6).